This invention relates generally to testing, and more particularly to an automatic or "robot" operated tensile test specimen apparatus that embodies a novel specimen bar holder or magazine.
In the polymer industry it is known to utilize uniaxial tensile tests to define and characterize the physical properties of both research and quality control samples of the polymer and like plastic materials. Basically, the test determines the stress on the test specimen as a function of strain under a defined set of experimental conditions. From the data such characteristics as tensile strength, ultimate strength, and modulus of elasticity may be ascertained.
In performing the aforesaid tensile test, a dumbbell-shaped test specimen is secured at its opposite ends in a testing machine. One end of the specimen is attached to a fixed grip and the other end is attached to a cross head which may be driven at a constant velocity. At one of the two grips for the test specimen there is a load cell to measure the amount of force on the specimen when it is in tension. The data may be accumulated in the form of force as a function of elongation, the increase in length as compared to original length, and other data. From such information it is possible to compute a number of physical properties, for example tensile strength at yield, yield strain, modulus of elasticity, and the like.
Tensile testing apparatus has been known for years, and generally these instruments require that the test bars be inserted and removed by hand. The relatively short duration of the tensile test makes it necessary for the operator to remain at the instrument in order to keep it in continuous operation. This of course increases the cost of performing the tests and ties up an operator who might be doing other work.